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Every year, people around the world celebrate a special set of numbers that begin 3.14 on the 14th day of the third month of the year (that’s today). Pi is the ratio of a circle’s circumference to its diameter – and no matter how large or small the circle is a constant number, the ratio will always be the same. Celebrate Pi Day by gorging yourself on (what else?) a slice of pie, and read up on 3 + 1 + 4 facts about Pi to impress your friends.
Plenty of great minds have devoted their lives to studying Pi, but there are two well-known geniuses who have a different connection to the mathematical constant. Famed theoretical physicist Albert Einstein was born on March 14 – which just so happens to be Pi Day. If that wasn’t spooky enough, astrophysicist Stephen Hawking died on March 14 last year.
Pi gets its name from the 16th letter of the Greek alphabet, π, which is also the first letter of the Greek word for “periphery”. As Pi is the ratio of a circle’s circumference or “periphery” to its diameter, the name is pretty apt. It’s also a lot easier to remember than the Latin phrase which was previously used to denote the ratio: quantitas in quam cum multiflicetur diameter, proveniet circumferencia (the quantity which, when the diameter is multiplied by it, yields the circumference). It doesn’t exactly roll off the tongue, so in 1706, a Welsh mathematician named William Jones began using the name Pi instead. (That also means that next year, the name Pi will turn 314 years old!)
Scientists and mathematicians are very precise about when celebrations for Pi Day should begin. They like to wait until 1.59pm, because that way, the date and time combine to make the first six digits of the number Pi (3.14159) in the US date format. If you’re going to devote a day to a ratio, you may as well do it properly.
In 1854, a mathematician named John Taylor proposed the idea that Pi inspired the design of the Great Pyramid of Khufu at Giza in Egypt. If you divide the perimeter of the pyramid by its height, the result is pretty close to 2π. Meanwhile, if you divide the circumference of a circle by its radius, you also get 2π. Taylor suggested that the Great Pyramid was therefore meant to represent the spherical Earth.
As pleasing as this theory is, it’s often disputed by mathematicians who point out that the Egyptians were rather good with numbers, and if they’d wanted to incorporate Pi in one of their pyramids, they would have done it perfectly, rather than just getting close.
Humans can never find all the digits of Pi, because it is never ending. Still, that hasn’t stopped mathematicians throughout history from trying. Some 4,000 years ago, the ancient Babylonians calculated Pi as 3.125 (which is pretty close!). By 1665, British mathematician Isaac Newton had worked out the first 16 digits of Pi – impressive, considering he did it without the help of computers. With the advent of new technology in the second half of the 20th century, the number of known digits of Pi increased to 500,000. But even that’s nothing compared to the record set in 2017, when a Swiss scientist used a computer to calculate more than 22 trillion digits of Pi.
English and maths might be completely different subjects in school, but linguists found a way to marry the two with Pilish – a form of constricted writing, or a way of writing that is bound to a certain set of rules. Anything written in Pilish has to consecutively follow the digits of Pi in length. The first word has to have three letters, the second has to have one, the third has to have four, and … well, you get our meaning. We imagine that it would be hard enough to come up with a poem (or piem) that makes sense and sounds good at the same time, but author Michael Keith wrote an entire collection of poems, short stories, etc, and titled it Not A Wake: A Dream Embodying (Pi)’s Digits Fully For 10,000 Decimals. The price on Amazon for the Kindle version? US$3.14 (HK$25), naturally.
There are several contenders for the person who has memorised the most decimal places of Pi. The Guinness World Records officially recognises a man called Rajveer Meena, who rattled off 70,000 digits in nearly 10 hours in India, on March 21, 2015. Beating him by a few digits more is Suresh Kumar Sharma, also of India. He recited 70,030 digits in 17 hours, mere months after Meena. Sharma isn’t recognised by Guinness World Records, but is by the Pi World Ranking List. Beating both of them, however, is Akira Haraguchi, who recited 100,000 digits of Pi from memory in 16.5 hours at a public event in Japan in 2006. In 2015, he told the British newspaper The Guardian he had memorised a further 11,700 digits. Feeling appropriately inadequate yet?
The sequence 123456 does not appear anywhere within the first 1,000,000 digits of Pi. Each digit from zero to nine, however, does end up appearing within the first 1,000,000 fairly equally. If we counted the number of times zero appears, it would be 99,959. There are 99,758 ones, 100,026 twos, 100,229 threes, 100,230 fours, 100,359 fives, 99,548 sixes, 99,800 sevens, 99,985 eights, and 100,106 nines. Put that information into a pie (ha!) chart, and you’d get fairly equal slices representing all the digits.